Double ignition system for internal combustion engines, ignition plug for double ignition systems, and electric spark generator

ABSTRACT

A double ignition spark plug has a cavity which is evacuated of substantially all gasses. The insulation portion of the spark plug is formed in two steps at a temperature of 800° to 1000° C. where the first sintering step is when the cavity is open and a first conductor is in place, and a second sintering step is effective to close the cavity and fix a second conductor in place. At least the second sintering step is conducted in a vacuum. The completed double ignition spark plug has substantially all gasses removed from the spark gap within the insulator.

This application is a continuation of application Ser. No. 08/190,004,filed Jan. 21, 1994, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technical field of ignition plugs forinternal combustion engines using gasoline as fuel. The automobilemanufacturing industry and the aircraft manufacturing industry usinginternal combustion engines make sincere efforts to decrease noxioussubstances like nitrogen oxides such as nitrogen dioxide and carbonoxides such as carbon monoxide contained in the exhaust gas emitted fromengines, as efforts for developing low-pollution engines.

The present invention has been achieved to meet the demand forlow-pollution engines. In the double ignition type ignition plug of thepresent invention, a sealed cavity is formed in the insulator outsidethe ignition plug, and electric arc rods are provided as parts of thefeeder circuit in this cavity, to face each other with a clearance ofabout 10 mm kept between them. A spark is discharged in this clearance,and simultaneously, the largest possible powerful electric spark isgenerated at the ignition port element of the ignition plug. In thisstructure, electric sparks are generated simultaneously at two points byone ignition plug; inside and outside a cylinder of an engine. Thissystem allows large electric sparks to be generated for perfectcombustion of fuel gas. So, the ignition plug for double ignitionsystems can decrease the concentration of noxious substance in theexhaust gas by more than 60% compared to the conventional ignition plug,and can enhance the output of the engine of the same type by about 25%,for greater contribution to the traffic industry and the transportindustry.

On the other hand, the electric spark generator of the present inventionis used in combination with a conventional ignition plug, and since itis the same as the above double ignition type ignition plug in effectand action, it relates also to the same technical field.

2. The Prior Art

The conventional ignition plug for internal combustion engines adopts asingle ignition system in which an electric spark is generated in aclearance of about 1 mm in the ignition port element of the ignitionplug in a cylinder of an engine, for explosion of fuel gas. The effortsmade by respective manufacturers of internal combustion engines fordeveloping low-pollution engines have been centered on the improvementof the engine itself such as the CVCC (compound vortex controlledcombustion) engine with a sub combustion chamber in addition to a maincombustion chamber, and the catalytic methods for decreasing noxioussubstances in the exhaust gas. The CVCC engine is not used any moresince the burning of lean mixture lowers the engine output, hence,lowers the driving performance and quality which the tomobiles areexpected to achieve. On the other hand, the catalytic methods cannot besaid to be perfect due to many problems such as the dissolution of thecatalyst caused by imperfect combustion of fuel gas, even though thecatalytic methods are mainly pursued for the development oflow-pollution engines. In addition, the improvement of the engine itselfand the adoption of any catalytic method require large costs. In thissituation, little efforts have been made for the improvement of theignition plug itself which has been made in the present invention.

SUMMARY OF THE INVENTION

This double ignition type spark plug has a cylindrical cavity enclosedas shown by symbol A in FIG. 2 which is within the portion or insulatingoutside of the ignition plug. The electric arc rods of nichrome wires,tungsten, or brass, are installed with a clearance of 5-15 millimeters(about 10 millimeters ideally) in the cavity. The cavity has a 7 mmdiameter and 15 length. The spark is discharged at the gap within thecavity, and the discharge causes the charge to be collected in theconductor wire extending from the cavity to the ignition port element ofthe ignition plug. This increases the current at the ignition portelement of the ignition plug and causes a large and powerful spark to begenerated simultaneously in a structure. This generates electric sparkssimultaneously at two points inside and outside of the automobilecylinder, i.e. sparks are generated in the cavity and at the ignitionport element. The spark is sharp and short in duration, and the noisegenerated by the discharge spark in the enclosed cavity does not escapeor leak to the outside. In this manner the engine remains or is keptsilent.

During construction, the insulator outside of the plug is sintered intwo steps at optimum temperatures of 800°-1000° C. The sintering of thefirst step is effective to form the cavity (partially) which cavity isleft open, and the sintering step fixes the conductor extendingtherefrom into the ignition port element. The second sintering stepcloses the cavity and provides for insulation of the electric rods inthe cavity and fixing of the conductor extending therefrom to aconnection terminal of the spark plug.

The present invention provides a new ignition plug which has never beenconsidered, i.e., a double ignition type ignition plug which allowselectric sparks to be generated simultaneously at two points inside andoutside a cylinder of an engine, and the electric spark generated at theignition port element of the ignition plug is so large and powerful asto achieve perfect combustion of fuel gas, for improving the combustionrate and halving the concentration of noxious substances in the exhaustgas, thereby enhancing the engine output. This can be said to be theleast costly economical engine improvement method which can achieve alow-pollution engine simply by improving the ignition plug.

On the other hand, the electric spark generator of the present inventionis used in combination with a conventional ignition plug (singleignition type), and this combination achieves the same double ignitioneffect as described for the above double ignition type ignition plugunprecedentedly.

The nitrogen oxides such as nitrogen dioxide, carbon oxides such ascarbon monoxide, etc. contained in the exhaust gas emitted from theinternal combustion engines of automobiles, etc. seriously affect humanhealth especially in recent years. The people are highly concerned aboutglobal environmental pollution, and the industries concerned areseriously grappling with the prevention of environmental pollution.

The technical problem to be solved by the invention is to lower theconcentration of the above mentioned noxious substances in the exhaustgases emitted from internal combustion engines as part of the efforts todevelop low-pollution engines useful for the prevention of airpollution. It is also intended to improve the output performancerelative to the engine capacity.

The problem can be easily solved by improving the combustion rate of thefuel gas in the internal combustion engines by achieving more perfectcombustion of fuel gas. The more perfect combustion of fuel gas can beachieved by generating larger and more powerful electric sparks at theignition port element of the ignition plug in a cylinder of an engine,and this is surmised to be the best solution of the problem. Under thisconcept, the double ignition system and the double ignition typeignition plug of the present invention have been completed.

The double ignition type ignition plug can generate incomparably largerand more powerful electric sparks at the ignition port element of theignition plug than those generated by the conventional single ignitiontype ignition plug, and allows the fuel gas in a cylinder of an engineto be burned almost perfectly, for lowering the concentration of saidnoxious substances in the exhaust gas by more than about 60%. Inaddition, the improved combustion rate raises the output of the engineof the same type by about 25% very effectively for improvement of engineperformance.

For the double ignition type ignition plug, a cylindrical cavity (ofvacuum ideally) enclosed in the porcelain or insulator outside theignition plug is formed, and in the cavity (7 mm in diameter and 15 mmin length), electric arc rods of nichrome wires, tungsten or brass areinstalled to face each other with a clearance of 5 mm to 15 mm (about 10mm ideally) as parts of the feeder circuit, so that a spark may bedischarged at the clearance. The spark discharged in the cavity causesmany charges to be collected in the conductor extending from there tothe ignition port clement of the ignition plug, and at the ignition portclement of the ignition plug, a grown current discharges a large andpowerful spark simultaneously. The electric spark generated at theignition port clement of the ignition plug caused by the sparkdischarged in the cavity is sharp and short in duration. Furthermore,since the spark is discharged in the enclosed cavity, the noise due tothe spark discharge does not leak outside, to keep the engine silent.

The clearance at the ignition port element of the ignition plug issomewhat wider than that in the conventional single ignition typeignition plug, i.e., 1.1 mm to 5 mm (about 1.8 mm as an optimumclearance) for generating a larger electric spark.

The sintering for the outer insulator of the double ignition typeignition plug is effected in two steps; the sintering for forming thecavity followed by the sintering for sealing the cavity. The insulatorsintering temperature is about 800° to 1,000° C.

On the other hand, the electric spark generator of the present inventionis to be connected with the connection terminal 3 of a conventionalsingle ignition type ignition plug. As shown in FIG. 3A, a cylindricalcavity (of vacuum ideally) enclosed in a porcelain or insulator cylinderis formed, and electric arc rods of brass are installed to face eachother through a clearance of 5 mm to 15 mm (about 10 mm ideally) asparts of the feeder circuit in the cavity (7 mm in diameter and 15 mm inlength).

If an electric spark is generated at the clearance, it causes manycharges to be collected in the conductor extending from there to anignition port element of the ignition plug. As a result, the currentincreased at the ignition port element of the ignition plug generates alarge electric spark. The electric spark generator combined with aconventional ignition plug forms a double ignition system whichgenerates two electric sparks simultaneously, and the effect achieved bythe electric spark generator is quite the same as achieved by the doubleignition type ignition plug. The electrodes at both the ends of theelectric spark generator are made of brass, and are connected with anignition plug by a socket and plug to allow disconnection, consideringthe life of the ignition plug.

An advantage of the present invention over the prior art is that thedouble ignition type ignition plug can lower the concentration of thenoxious substances in the exhaust gas emitted from engines by more thanabout 60% compared to the conventional single ignition type ignitionplug. This effect allow the engines to simply conform to the Muskie Lawin U.S.A. While the decrease of the above mentioned noxious substancesby any improved engine (CVCC engine, etc.) or any catalytic method isvery costly, the present invention is very economical since the intendedeffect can be achieved simply by improving the ignition plug. Inaddition, it can enhance the combustion rate, for raising the engineoutput by about 25%.

On the other hand, the electric spark generator of the present inventioncan be used in combination with a conventional single ignition typeignition plug, to form a double ignition system, and since it also actssimilarly, its effect is quite the same as that of the double ignitiontype ignition plug. This configuration is unprecedented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a sectional view showing the double ignition type ignitionplug of the present invention, based on which the idea of the presentinvention could be created.

1. Sealed Cavity to be generated Electric Sparks by Electric Arc Rods

2. Ignition port Clearance

3. Connection Terminal

FIG. 2A is a preferable sectional view showing the double ignition typeignition plug of the present invention in detail.

1. Sealed Cylindrical Cavity

2. Ignition Port Clearance

3. Feeder Connection Terminal

4.5. Brass Central Electric Axis

6.7. Nichrome, Tungsten, orBrass Electric Arc Rod

8. Clearance

9. Porcelain or Insulator Isorate Material

11. Metal Cace

12. Iron Screw Fit to Engine

13. Eeath Element

15. Ignition Port Element

FIG. 3A is a sectional view showing the electric spark generator of thepresent invention, to be combined with a conventional single ignitiontype ignition plug, for forming a double ignition system.

1. Sealed Cylindrical Cavity

2. Connection Socket

3. Feeder Connection Terminal

4.5. Brass Electrode

6.7. Brass Electric Arc Rod

8. Clearance

9. Porcelain or Insulator Cylindrical Isorate Material

10. Anti Heat Rubber

FIG. 4A is a sectional view showing a conventional single ignition typeignition plug.

1. Ignition Port Element

2. Ignition Port Clearance

3. Connection Terminal

DETAILED DESCRIPTION

The present invention is described below in more detail in reference tothe attached drawings.

The description for FIG. 1A is not made here.

FIG. 2A is a sectional view showing the double ignition type ignitionplug in detail. The discharge of a spark at the clearance 8 between thearc rods 6.7. facing each other in the cylindrical cavity 1 enclosed inthe insulator isorate material 9 indicated in this drawing is a majoridea of the present invention. A spark is discharged at this clearance8, and simultaneously a powerful and large spark is generated at theignition port element 15 (or at the ignition port clearance 2) of theignition plug. At two points of one ignition plug, sparks are generatedsimultaneously. This is the double ignition of the present invention.

As shown by this drawing, in the cylindrical sealed cavity 1 (of vacuumideally) of 7 mm in diameter and 15 mm in length enclosed in theinsulator isorate material 9 outside the ignition plug, the arc rods6.7. of tungsten or brass are installed to face each other with aclearance 8 of about 10 mm as parts of the feeder circuit, and a sparkis discharged at the clearance 8. The clearance 8 between the arc rods6.7. can be adjusted to generate the largest possible electric spark. Ifa spark is once discharged in the cavity 1, a sharp, large and powerfulelectric spark is generated at the ignition port element 15 of theignition plug.

The clearance 2 of the ignition port element 15 of the ignition plugshown by this drawing is adjusted to be somewhat wider than that of theconventional ignition plug, i.e., about 1.8 mm, since the charges areincreased by the action of double ignition, to increase the current.

The numeral number 3 in this drawing denotes the connection terminal ofthe ignition plug to the feeder.

The outer insulator portion of the ignition plug is sintered in twosteps. The optimum sintering temperature is about 800° to 1,000° C. Thesintering of the first step is effected to form an open cavity 1 in theinsurator isorate material 9. The sintering of the second step toenclose the cavity 1 is effected to install the arc rods 6.7. in thecavity 1 and to fix the two central electric axes 4.5. extending fromthere to the connection terminal 3 and on other hand, to the ignitionport element 15.

The double ignition type ignition plug can be used to lower theconcentration of noxious substances in the exhaust gas emitted from theengine by more than about 60% and enhance the engine output by about25%.

The electric spark generator shown in FIG. 3A is described below.

The electric spark generator is connected to the connection terminal 3of the conventional single ignition type ignition plug shown in FIG. 4A,for use as a double ignition system. As shown in FIG. 3A, thecylindrical cavity (1) (of vacuum ideally) enclosed in the cylindricalinsulator (9) is formed, and the arc rods (6.7,) of brass are installedto face each other with a clearance(8) of about 10 mm as parts of thefeeder circuit in the cavity (1)(7 mm in diameter and 15 mm in length),to discharge a spark at the clearance (8). The clearance (8) should alsobe desirably adjusted to generate the largest possible electric spark.

The electrodes (4 and 5) at both the ends of the electric sparkgenerator are also made of brass, and are connected with the ignitionplug by a socket (2), to allow easy disconnection from the connectionterminal of the ignition plug, considering the life of the ignitionplug. The socket is protected by resistant rubber (10). The numeralnumber 3 in this drawing denotes the connection terminal to the feeder.And as all parts (brass electrodes (4.5.), cylindrical insulator isoratematerial (9), anti heat rubber (10)) of the electric spark generatoradopt method of screw, so that, is very easy to be fit together.[Industrial Applicability]

The double ignition system, double ignition type ignition plug andelectric spark generator of the present invention can be used in theautomobile manufacturing industry and the aircraft manufacturingindustry which are making efforts to lower the concentration of noxioussubstances like nitrogen oxides such as nitrogen dioxide, carbon oxidessuch as carbon monoxide, etc. contained in the exhaust gas emitted frominternal combustion engines by improving the engines and adopting newcatalytic methods.

I claim:
 1. A double ignition spark plug constructed by a processcomprising the steps of:making an iron base; forming an insulatorextending through said iron base; forming an ignition spark gap at saidiron base by extending a first conductor through said insulator andextending towards a portion of said iron base; forming a cavity in saidinsulator; extending said first conductor into said cavity; extending asecond conductor into said cavity and forming a space between said firstand second conductors within said cavity; evacuating said cavity ofsubstantially all gases; providing a connecting terminal on saidinsulator; and connecting said second conductor to said conductingterminal.
 2. The method in accordance with claim 1 further comprisingthe step of sintering said insulator in two steps at temperatures of800°-1000° C., wherein said first step is when the cavity is left openand the first conductor is in place, and wherein said second sinteringstep is effective to close said cavity and to fix said second conductorin place.
 3. The method in accordance with claim 1 further comprisingthe step of making the clearance between said first conductor portionextending towards said iron to be 1.1-5.0 millimeters.
 4. The method inaccordance with claim 1 further comprising of forming one of said firstand second conductors of a material selected from the group consistingof nichrome, tungsten, and brass.
 5. The method in accordance with claim1 further comprising the step of forming said cavity to have a 7millimeter diameter and a 15 millimeter length.
 6. The method inaccordance with claim 2 further comprising the step of making theclearance between said first conductor portion extending towards saidiron to be 1.1-5.0 millimeters.
 7. The method in accordance with claim 2further comprising of forming one of said first and second conductors ofa material selected from the group consisting of nichrome, tungsten, andbrass.
 8. The method in accordance with claim 2 further comprising thestep of forming said cavity to have a 7 millimeter diameter and a 15millimeter length.
 9. The method in accordance with claim 3 furthercomprising of forming one of said first and second conductors of amaterial selected from the group consisting of nichrome, tungsten, andbrass.
 10. The method in accordance with claim 4 further comprising thestep of forming said cavity to have a 7 millimeter diameter and a 15millimeter length.